This disclosure relates to power distribution assemblies, and more particularly to disconnect mechanisms which rotationally couple a prime mover and a driven element together.
A driven element (aka driven equipment), such as electrical generators, pumps, and compressors are rotationally connected to a prime mover (aka power source), such as a main engine of an aircraft. This connection can occur with a shaft, also known as a drive shaft. While driven element is generally very reliable, it will be appreciated that there are times when the driven element may fail. Particularly in aircraft applications there is a need for the driven element to fail in a safe manner. However, the prime mover is not aware of a failure of a bearing in the driven element. Thus, the prime mover will continue to provide power to the failed driven element. Depending upon the failure mode, this continued supply of power can create an unsafe condition.
Further, this failure can cause increased stress to be placed on the prime mover. Additionally, when the driven element fails, it is sometimes possible for the internal components of the driven element to continue to rotate. However, this post-failure rotation mode can be especially taxing on the prime mover. Further still, this rotation of the internal components of the prime mover, in the post-failure mode, can result in additional damage occurring to the driven element. Thus, many devices and methods have been used in order to predict when a failure of the driven element would occur.
As is done with many aviation components, the driven element could be changed prior to failure based upon a preventative maintenance schedule. As will be appreciated, this schedule may not account for the exact conditions which have been subjected to the driven element. Thus, there is the chance that the driven element will not be changed before it would fail. Alternatively, there is also the chance that the driven element may be changed well before it fails, thereby sacrificing or wasting useful remaining life of the driven element. This results in increased maintenance costs and downtime.
Alternatively, some systems utilize a variety of sensors disposed within on near to the driven element. These sensors may measure, for example, temperature and/or vibration of the driven element or the surrounding area. Then, through a predictive model, an estimate is made of when the driven element may fail based upon the data obtained from the sensors. As such, the driven element can be changed prior to the estimated failure time. However, it is very expensive and time consuming to install these additional sensors in an attempt to determine when the driven element may fail. Further, these sensors and related computing equipment add additional weight to the aircraft.
Thus, to avoid the negative issues associated with a failure of the driven element, a user is forced to either preventatively change the driven element based upon a maintenance schedule or rely on expensive sensors to predict when the driven element may fail. Further, the aforementioned methods fail to address the situation of rapidly occurring types of bearing failure modes where the predictive maintenance system cannot respond in time to prevent failure of the entire assembly.